N.Y.C. Admin. Code § 27-702: § 27-702 Uplift capacity.

A minimum factor of safety against withdrawal of two shall be provided, except that the factor of safety against withdrawal shall be greater than two when the piles are subjected to dynamic uplift loads. The uplift capacity shall be demonstrated by pull-out tests, except where a factor of safety of three or more based on analysis is used, pull-out tests need not be conducted.